The popularity of wireless power transfer for charging energy storage devices and/or powering electronic devices is growing rapidly. For example, mobile electronic devices are now widely used, and are likely to see increased use in the future. Mobile devices are generally powered by batteries or other energy storage devices that must be recharged at regular intervals. Recharging may be accomplished via a wired or wireless connection to a power source. Wired charging requires that the device being charged be connected to a power source via a charging cable, which can sometimes be inconvenient. In contrast, wireless recharging systems transfer power without connective cabling and consequently can provide a much more convenient charging experience than wired chargers.
Wireless power transfer is also advantageous for reasons other than convenience. For example; wireless power transfer is well-suited for use in industrial environments, where sparks from a wired charger could ignite explosive gases, and for use with biomedical devices that require sterile, hermetically sealed cases.
To facilitate power transfer over longer distances and to allow for reduction in size of system passive components (e.g., inductors), the frequency of operation of wireless charging systems is increasing.